


The Time Traveler's Babysitter

by Phandancee74



Category: Supergirl (TV 2015)
Genre: Almost a kid fic, Baby Superman, Barry Allen Can't Math, F/F, Fix-It of Sorts, Lena Luthor Finds Out Kara Danvers is Supergirl, Protective Lena Luthor, Time Travel, married supercorp
Language: English
Status: Completed
Published: 2020-05-07
Updated: 2020-05-07
Packaged: 2021-03-02 18:07:13
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,685
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24061063
Author URL: https://archiveofourown.org/users/Phandancee74/pseuds/Phandancee74
Summary: Since moving to National City, Lena Luthor's world has gotten weird. After today though, she's got a good idea of what her future looks like.
Relationships: Kara Danvers/Lena Luthor
Comments: 8
Kudos: 301





	The Time Traveler's Babysitter

Lena was sitting at home, glad that everything at L corp was going well for once, she was finally unpacked from her move to National City, and she was even starting to make a friend. She would probably head into the office in a few hours, even though it was Saturday, because there wasn’t much else to do with her life right now. Lena was dedicated to helping National City and rebuilding L Corp to be a force for good, it kind of made her a workaholic, but she loved every minute. She decided she might just finish reading Kara’s latest article first, the girl had been really excited about it and told Lena all about her research and interviews the last time they had lunch. She was just opening CatCo to the relevant page when suddenly there was a visual disruption in the middle of her living room. A man in a red suit came out of it carrying a baby. 

“Lena? Oh man, my timing is perfect! I knew I could get here before you left for work.”

“Do I know you?” Lena asked. The man had called her Lena, not Lena Luthor, or just Luthor, which was a good sign in that he probably wouldn’t attack her for the actions of her brother, but also indicated a friendliness she didn’t expect from strangers.

“Do you not remember me, Lena? Oh man. That is so mean. It’s Barry!”

Lena frowned and shook her head.

“Oh no, am I in the wrong universe? You do know Kara right?”

Lena nodded a little thrown off by the question and Barry sighed in relief. “Perfect. I swear if this is another one of your jokes, Lena, I just don’t have time for it today. Here can you take this little guy?” Lena put her arms out automatically and was handed the baby. “Kara said you have experience with Kryptonian babies and I thought she said you were expecting him. Anyway, I gotta run, but we will be back for this cute fella later, just had to drop him off somewhere he wouldn’t be looked for.” With that the man disappeared.

Lena looked down at the tiny bundle in her arms. “Oh yeah, no one would look for a Kryptonian with a Luthor, that’s for sure. What the hell was Kara thinking?”

The baby was awake and looking up at her. With his dark hair and her knowledge of the history of Krypton, Lena assumed this bundle of joy belonged to Superman. “I didn’t know Superman had a baby. I guess you’re a little secret aren’t you? I don’t know why they left you with me buddy, but you’ll be okay. We are not going to L corp though.” Lena tried not to imagine the rumors that would get out if she walked around with a baby, especially if she could not provide more information on the parents. Maybe in a few years National City would have enough trust in a Luthor to not think “baby stealer” a likely moniker for one. 

Lena took SuperSon back to the couch and sat down. She thought about what she knew about Superman’s powers. He had flight, x-ray vision, heat vision, and cold breath. “You aren’t going to burn me to death with your eyes, are you SuperSon?” The baby did not reply. Lena sighed and thought about trying to call Kara but realized that if Kara had told the red suited man to leave the baby with her, then Kara was probably too busy to respond right now. She also thought that it must be pretty important and secretive, as Kara’s sister worked for the government and Kara had still chosen her. “Experience with Kryptonian babies? What the hell, Kara?” SuperSon smiled and giggled a little at that. “You’re too small to pick up swear words aren’t you Little Kryp? Oh god, I better check. I can’t turn you down an immoral path as a baby, Lex and Lillian would be too proud.”

Lena spent an hour looking things up on her laptop and checking on the baby every few seconds just in case he stopped breathing or started crying. The kid was really well behaved and had fallen asleep soon after they sat down. Lena had been worried he died for a second but then waited a moment and saw his chest rise and fall repeatedly. Based on her initial research on human infants, and that could be a terrible baseline to use but it was all she had right now, SuperSon appeared to be about six months old. Lena was really content to let the baby sleep on her for now until Kara or Barry(?) returned for him. Maybe he’d sleep the rest of the time they were gone. 

Lena liked kids but had very little experience with them. She had been the youngest Luthor since she was adopted by them and had been taught that having kids was usually a mistake, especially for a woman in power. Lena spent a few minutes just sitting there watching SuperSon exist and thinking what she could possibly do to keep him safe if this went on longer than a few hours. Lena knew that most things couldn’t hurt a Kryptonian, though she was still checking for breathing regularly because she was pretty sure they needed air, but she had heard of Kryptonite. If someone showed up with ill intentions towards SuperSon and they had Kryptonite, she needed a way to stop them. Given a way to use her problem solving mind instead of her limited keeping a baby alive experience, Lena jumped into action, metaphorically. Literally she stayed on the couch so as not to wake SuperSon.

\-----------------------------------------------------------------------------------------------------------------------

“Give me the baby, Lena.”

Lena looked up from her notes to see her brother standing suddenly in front of her. Clearly there was technology that made doors unnecessary and she really needed to invest in better security. There was also something off about her brother. “Green and purple, Lex? I mean, I know you haven’t been able to dress the way you’d like in prison but I didn’t know you were that fashion starved, I would have sent you an orange ascot.”

“Hah, hah little sister. Give me Superman, now.”

Lena looked down at the baby in confusion. “Superman? I believe you mean SuperSon. Superman is an adult, Lex. This is a baby.”

“Yes, obviously. I went back in time to kill baby Superman and what do I find but an empty cradle? Damn heroes found out my plan somehow.”

Lena let this all sink in. Time travel, Superman, other heroes? She guessed Barry was a hero then. She calmly pressed a button on her watch and decided to keep Lex talking. “So this is Superman? I thought he’d be taller.”

“Lena, you already made the baby joke. You only get one. Now hand him over already, would you? Those irritating do gooders should be back any moment.”

Baby Superman began to cry as Lex approached him. “Yes, that’s right little alien, cry. From today all of humanity will be safe from you.” Lena rolled her eyes. “You will rue the day you came here and decided to take us on.” Lex raised his arm and a gun formed from his hideous suit. It began to glow green as it charged up and Lena couldn’t take her eyes off of it. She really should have been looking at the baby but she couldn’t help trying to mentally break down how the weapon was constructed.

A shot went off and then Lex went flying across the room and knocked his head against Lena’s kitchen counter, his head rolled to the side and Lena figured he had knocked himself out for the moment. Now she turned her attention back to SuperSon, scratch that, Superman. The baby was surrounded by a slight red glow which disappeared when Lena tapped her watch again. 

“I cannot believe Kryptonians lived on a planet that they were naturally allergic to. Thank goodness your sun cancelled out that allergy. Throw in a simple energy rebound and you are Lex-proof!” She went to pick up the baby but was surprised when she received a kiss on the cheek and the baby was gone from the couch. 

“Thanks, Lee.” Supergirl said, holding the baby in her arms. “Man, you know I haven’t held this baby in my arms in, Rao, fifty years, is that right?”

Lena reached up and touched her cheek. “Ummm.” she managed to say. “Ummmm, Supergirl?”

Supergirl looked at Lena, confused, and then her face went wide with horror. She handed baby Superman back to Lena and raced around Lena’s apartment. “BARRY ALLEN I AM GOING TO KILL YOU!”

The man in red was back as well apparently, but Lena had missed him while trying to understand Supergirl’s sudden affection for her. Barry was over next to Lex, putting some special cuffs on him. “What did I do this time, K-” Supergirl interrupted him by literally racing across the room and putting a finger against his lips. 

“You shut up, Flash. This is not where you were supposed to go. You were way off.”

“What?” Barry, the Flash(?), seemed insulted. “No. Lena said she knew you. She took baby Supes and look, she took down Lex like a pro.”

“Yeah, that is because my w-, damn it, Lena, is a badass no matter when you travel.”

“So you are time travelers too?” Lena asked. 

Supergirl sighed. “Yes. We are, and actually,” She tilted her head a little. “This is starting to make some sense. I guess I have a few things to tell you, but let’s start with, I’m from the future. Barry Allen was supposed to drop my cousin off with You six years in the future.”

Barry blushed. “I see the issue now in my calculations. You told me the best time to drop him off would be six _hours_ earlier today, before Lena left for her board meeting. I may have calculated for six _years_ back from our today.”

Supergirl gave him a look. “Yeah, just maybe. Lena, I am so sorry about this but we kind of need to leave Superman with you for a bit longer, it really isn’t ideal to do too much time travel, affecting timelines and all that. I swear, we will be back as soon as we can. You are doing an amazing job as ever, Babe.” Barry gave Supergirl a look just as she realized what she’d said, they both made faces and sighed deeply. “Shit. Okay, see you later.” With that both of them disappeared again, taking the unconscious Lex with them.

Lena looked at the bundle in her arms, who had just gone back to his nap. He was suddenly the least confusing part of her day, and he was a time traveling alien baby. “I guess I just saved Superman’s life. That’s good, because you become pretty important in the future, little Kryp. Also, I guess Supergirl and I get together? So she would be pretty upset if you died. How old is she? She said she hadn’t held you in fifty years. Maybe that’s more time travel. I’m going to start a timeline.”

Lena spent a few minutes learning how to make a sling to carry Baby Supes in and then the two of them got to work with their timeline. Lena asked questions every now and then of her research buddy, but unfortunately he had few answers. “Babies on earth don’t usually speak at six months, but maybe you do. Though I guess if you could talk you’d speak Kryptonian? Maybe I will learn Kryptonian in the future. Then I can speak it to all the other Kryptonian babies I babysit.” Lena was joking and then remembered what Barry had said when he first dropped off her alien assignment. “There are going to be future Kryptonian babies for me to watch. Maybe I will get to hang out with a future SuperSon, or SuperDaughter? OR!!” Her brain started to melt a little here. “Maybe I have my own SuperSon or SuperDaughter?” Lena was freaking out, did kryptonian fetuses still have super powers? How would she survive having a flying fetus trapped inside her for nine months? What if kryptonian gestational periods were longer, could she survive two years of alien babies? However she was still very much focused on her project so she dutifully added to the six years from now section of her timeline “Little Kryps. How many?” 

A chime went off and then Lena saw Supergirl sitting on her couch. “What was that sound?” Supergirl asked, looking around.

“My new doorbell for guests who refuse to use doors.” Lena smiled, she was quite proud it worked. 

“That’s pretty smart.” Supergirl replied. “But maybe you should make it less obvious? So that future visitors don’t know that you know they are there. Gives you back an element of surprise. I mean, I didn’t know you’d ever invented one of these, so I’m going to assume you put in a mute function at some point.”

Lena nodded. “That is much sneakier, much more Luthor of me.”

“Luthor can mean clever, Lena. It doesn’t have to mean evil. You should know, you taught me that.” 

Lena was happy to hear her future girlfriend, partner, baby mama(?) refer to Luthors that way. “So I assume you came to pick up baby Superman?”

“I did. But I think it’s time I told you something important. I mean, in the future you already know it, but I’m mostly sure I’m not messing anything up by telling you now.”

“I am wondering how time travel works.” Lena said.

“I don’t want to get into that too much, Lee. It makes my head hurt.” Lena caught it again, Supergirl’s usage of a nickname for her. Supergirl had called her Lee twice now and Babe once.

“Okay, just tell me whatever it is that you want to tell me Supergirl. Then I have a few questions, Babe.” Lena said the last word teasingly.

“Right. Yeah, that was not supposed to come out but I’m the worst at this kind of thing.” Supergirl led Lena back over to the couch so they could both sit and look at the baby. Lena gave a nod to get Supergirl talking again.

“Okay. So I did a quick check the last time I came here when we grabbed your brother. It looks like six years before my current time but I want to make sure that we’re on the same page. How long have you lived in National City?”

“Three months.” Lena replied.

“Right. So you’ve met me, as in Supergirl, a few times then?”

“Yes. You’ve saved my life at least five times by now.” Lena laughed. “I guess you must do it a few more times if we’ve grown as close as I think we have.” 

Supergirl blushed. “Yeah. I mean. Hold on. What I have to tell you isn’t about Supergirl.”

Lena frowned. “It isn’t?”

“No. Lena, Supergirl isn’t all of me. I have a secret identity, or rather Supergirl is my other identity.”

Lena thought for a moment. “That makes sense. I mean, you could do the Supergirl thing full time but I’m sure you have friends and people you know outside of saving the city day in and day out.”

“Exactly.” Supergirl said. “I want you to know who I really am. But you have to understand that this is future me telling you who I am. Current me will not know that you know and you can’t tell her. You need to let her tell you.”

“Do I even know your other identity, Supergirl? I’ve only been in National City for three months, I barely have a single friend. OH MY GOD YOU’RE KARA DANVERS.” Lena’s shout got baby Superman to wake up again and look at her funny but a moment later he giggled.

“This! This is what I was expecting when I told you the first time.” Kara said, feeling vindicated. “It is not what I got, and now I know why. You told me, in the future, that you already knew. I mean, I know someone else told you, okay I need to stop talking about this anymore. Look, just ask me a few questions and I will tell you all that I can. I just, I wanted to tell you now. When I should have told you all along. I trust you, Lena. I want you to know this is not and never will be a trust issue. It’s a safety issue, even then, it’s still wrong.”

Lena’s head was spinning. “When do you tell me? The You that will be from the same time as me.”

Kara smiled sadly. “That is definitely too much information, but I can say I tell you too late. I knew from the moment I met you, Lena, that you were someone special. Someone I could trust. I listened to others and I shouldn’t have.”

“Why can’t I just tell you now that I know?”

Kara frowned. “That gets into time travel and changing timelines. I mean, if you want to tell me that you know, you can. I won’t stop you. I will tell you that six years from now, based on my theory that the future you has had this exact conversation, our life is amazing. If you want a shot at the life I have now, you can’t tell your Kara that you know.”

“That’s a lot to ask.”

“You’re Lena Luthor. You can handle it.”

Lena looked down at baby Superman. “When Barry dropped off this little guy, he told me that you said I’d had experience with kryptonian babies. Does that mean we have kids?”

Kara smiled softly and that was enough of an answer for Lena. “I swear I would love to tell you all about my future, but I really don’t want to mess up a single thing. Let’s just say you are very clever and,” Kara paused to look at Lena’s timeline. “Fairly close with that. By the way, if you want to keep that, shield it with lead and remove it from your apartment. I really can’t know about today for another six years.”

“I have to keep everything a secret for six years?” Lena asked, a bit put off by the idea.

“Not everything. Just the exact events of today. I mean, the number of times you’ve teased me about this without me getting it and the way you doubled over in laughter the first time you met Barry, all of that makes sense now. You were somewhat subtle, though you clearly enjoyed yourself. Though you keep teasing Barry about his equations. You’ve been giving him shit for years and now I know why.”

Lena laughed. “Okay. So, you’re Kara Danvers, my new friend.”

“Your best friend.” Kara interrupted, refusing to be less than that even during a serious conversation about her own failings.

“Okay, Kara Danvers, my best friend. And for the next several years we are both going to keep the same secret from each other?”

“Yes? Like I said, I will not change what happened today and I won’t mess with the timeline again. Barry has done it so many times I swear his timeline looks like Swiss Cheese. If you tell your Kara that you know I don’t know where your life will go. When I get back to the future I guess I’ll know just how patient and long suffering a Luthor can truly be.” Again Lena noticed that Kara said Luthor as if it were a name to be proud of, instead of a curse. That alone was almost enough to guarantee her silence, Kara’s smile when Lena had asked about children was enough to seal the deal. 

“One more question.”

Kara laughed. “I can’t believe it’s only one.”

“Will you get back the same day you left in the future? If you don’t will I be worried?”

“That is two questions, Lena. But I’ll answer them. God, I hope I get back the same day. My wife would kill me if I missed Lily’s birthday.” Kara joked, not noticing her slip and Lena didn’t let on. “You always worry about me, Lena. I always worry about you. That’s just the way things are,”

“When you’re married.” Lena supplied.

“Right.” Kara agreed, confused. “Rao, I did it again. Lena, I need to go before I tell you everything, I am the worst at this.”

Lena laughed. “You are surprisingly bad at it for a Superhero that keeps secrets all the time.”

“Just remember. I am so sorry about this one.” Kara looked like she was ready to cry. “This, telling you now, makes me so happy. I am sorry that I get this feeling, this joy, today and you have to wait. Live your life, Lena. Live it however you would if you didn’t know. Don’t wait for me, or try to help me, or anything. If I can’t tell you, then I don’t deserve to have you.” 

“Sounds like this is going to be rough.” Lena said, a tear starting to form in her eye. “How about one kiss from my future wife before you whisk this Kid back to the past and travel home into future me’s loving arms.”

“Okay. But only if you promise you won’t be mad at me in the future for this.” Kara joked and pulled Lena towards her. The two kissed for only a moment, but then Kara pulled back and kissed Lena’s forehead. “I would never be strong enough for this, Lee. You are so amazing.” With that she carefully took baby Superman into her arms and disappeared a final time.

“Oh Kara Danvers, my Supergirl. You bet your ass I’m not waiting for you. Six years from now I’m going to be the badass mother of kryptonian babies, I need to start prepping.” Lena went back to her timeline and started writing again “Lily Luthor-Danvers, b. 20--”

\-----------------------------------------------------------------------------------------------------------------------

Kara returned baby Clark to his cradle a few minutes after Lex’s attack, thankfully planned in the middle of the night. It was too early for Ma and Pa Kent to have to deal with any of this madness, at this point in their timeline they still weren’t sure if their new son could really be an alien. Kara was just glad her wife had tipped them off that morning about Lex’s plan. She then called Barry to grab her and help send her back to the future. 

“So, I’m never going to hear the end of this, right?” He asked.

“I mean, I think Lena and I both had a great day today. She’s still going to give you shit about confusing hours and years though. You understand that isn’t even like a decimal point error. You were way off.”

“I get enough of this from your wife. Just remember that we saved your cousin today and that I proved Lena is a BAMF in any timeline.”

“Barry, if I am not returned to my timeline and my wife and daughters, I will end you.”

“Right. Right. I’m pretty sure it’s fine, look there they are.”

Kara stopped outside her house, looking into her backyard where she could see her wife and daughters sitting on their patio. “Thanks, Barry. Are you coming over for the party?”

“What party?” Barry asked. “Isn’t that tomorrow?”

“Lily’s party is tonight.”

“No, it’s not. I told everyone else to come tomorrow.” Lena interrupted from over the fence. “Had to make up an excuse to get you to myself tonight. We’ll see you tomorrow Barry, or in six years, it’s so hard to tell.”

“Shut up, Luthor.” Barry gave Kara a hug and sped off.

Kara flew over the fence and raced to change before racing to the patio to see her family. “Are you all still you?” She asked as she quickly checked each of them for changes. Lily and Liza giggled at their mom's actions. “Wait, Lena. Why do our daughters have green tongues?”

“From their sperm donor, Brainy?” Lena said with a ‘duh’ tone in her voice.

Kara looked at her in dismay. “Their what? What!? Oh no, something got changed. I mean, it’s fine, everything is fine. We can live with this.”

“Good.” Lena said, seeming confused. “Now let’s go inside for the Queen’s speech. You know it’s mandatory.”

“Queen’s speech?”

“Yeah, Kara. The Queen of Daxam and Earth? Eve Tessmacher?”

Kara fainted. 

“Mommy, that was mean.” Lily said to Lena. 

“Yes, it was.” Lena agreed. “But I’ve been waiting six years to be able to tease your mom about this, and I had way too much ammunition.”

\-----------------------------------------------------------------------------------------------------------------------

A little later when Kara had woken up and her girls were in bed and no longer had green tongues, “Honestly Kara, it was popsicles, I didn’t even have to use technology to mess with you.” she sat with her wife on their couch, the same couch she’d sat on a few hours earlier while pouring out her apologies to the other Lena.

“I can’t believe you did it, Lena. I mean, I can of course, you’re amazing. Still, I’m so sorry. I know how hard it is to keep a secret, especially from those you love. You didn’t even love me yet, you barely knew me.”

“Kara Danvers, I’ve loved you far longer than you’ve let me. I think it all started for me the day a beautiful and strong Supergirl came into my apartment, kissed me on the check and trusted me with a secret and one of the most important people in her life.”

“So, I’m forgiven?”

“I told you that years ago, on the night we got together if I remember correctly, that I had forgiven you for keeping this secret. And I’ve understood why you kept it, every day. From the moment I was entrusted with Baby Clark I got why that secret was more precious than anything. When Lex told me you were Supergirl, it was my nightmare. The person I feared knowing your secret the most, because of what that could mean for you, for us, for our future kids. When you finally came clean, I wasn’t just upset that you hadn’t told me, but that future you had and that I had to wait to tell you the truth. I wanted to come clean with you, I have been waiting for Lily’s birthday for six years and cheering you on every day. You gave me so much hope that day. Hope that someone would love me the way you did that day, that you could trust a Luthor, that I could have everything I ever wanted and things I didn’t know I would. Every day you didn’t tell me, it tested that hope, but every time that Kara Danvers came to visit and brought me lunch, or wrote an article about me, or Supergirl saved my life again, that hope came flooding back. I knew I could wait.”

“So.” Kara said after letting Lena’s speech wash over her. “You’ve had a cheat sheet this whole time. How does it feel flying blind from here on out?”

“Oh, didn’t I tell you? Time travelers visit me all the time. I guess a Luthor can keep a secret better than a Super.”

Kara stuck her tongue out at her wife. “I kept my secret from you for years.”

“You kept it for three months, Hon.”

“You wouldn’t have figured it out if I hadn’t told you today.”

“I would have figured it out in another two weeks.” Lena said with certainty.

“Oh yeah?”

“Yeah. Because that’s when I first got video footage of you changing into your suit in an elevator. Do you know how many times I have had to delete footage because of you? We really need to work on your stealth, Babe.”

“Thank goodness I married such a wise and wonderful woman.” Kara said, defeated and madly in love as ever with her wife. 

“You’re pretty great yourself, Supergirl”

**Author's Note:**

> I could have worked on editing Chapter 7 of my ongoing SuperCorp story today, but I had this idea last night instead and it wanted to come out first.


End file.
